Office of Coast Survey - Historical Maps and Charts

A huge array of historical charts are available online:

Office of Coast Survey - Historical Maps and Charts

They use a goofy format, called MrSid, that must be decoded into something more sensible to use. I use the linux decoder created by Lizardtech found here. Once you decompress the image, you see why they use this format which compresses the image using wavelets.

Below is an image of a historical chart of the Mississippi River Delta first published in 1874 found by searching for key word 'Mississippi'. Click the image for a higher resolution image (still only 1/4 of full resolution).